1. Field of the Invention
The present invention relates to a valve main unit included in a valve device and to a method of manufacturing the valve main unit.
2. Description of Related Art
A valve device that controls a high-pressure hydrogen gas flow is provided in, for example, a fuel cell vehicle. The valve device includes: a valve main unit including a hydrogen gas channel; and a high pressure valve that controls a hydrogen gas flow (see JP 2013-029161 A and JP 2010-038247 A). In the valve main unit, part of the channel includes a valve housing portion that houses the high pressure valve. As described in the paragraph [0021] of JP 2013-029161 A, the valve housing portion is subjected to anodic oxide coating that includes anodizing of an aluminum alloy.
In a valve main unit in which a high pressure valve is provided, a relatively large fluctuation of hydrogen gas pressure occurs in a channel while the high pressure valve is operated. That is, a repeated load is applied to the channel due to the operation of the high pressure valve. Meanwhile, anodizing of a channel (valve housing portion) in a valve main unit made of an aluminum-based alloy has an advantage in terms of improving, for example, corrosion resistance of the channel. However, the above-described repeated load is applied to an oxidation layer formed by anodizing. Accordingly, there is room for improvement in increasing durability of the channel for the hydrogen gas against the repeated load.